At the risk of sounding like a crotchety old *NIX admin, please don't do strange and funky things like writing a ruby script to manage PATH for you -- You aren't going to be editing this very often (if you are you're probably doing something wrong), and you will be better served in this case by conforming to the same standards as everyone else, especially if/when you need to ask someone for help.

The colon-delimited path list isn't so terrible in the grand scheme of badly formatted things you'll find in the world :-)